Recently, in various fields such as a medical device, industrial, personal robot, micro-machine, the development of the micro-machine is promoted. Recently, when the semiconductor micro-fabrication engineering is applied, a micro-mini mechanical part or motor whose size is several μm can be made on a silicon substrate.
On the one hand, in the field of the electronics, such a trial that an actuator device, which is a basic movement region of the micro-machine, is fabricated by using an organic material instead of inorganic material such as silicon is brought into active. Because the organic actuator device has lightness in weight and flexibility in addition to excellent molding property, new and various application is expected.
Conventionally, in the case of the actuator which operates as a micro-machine, the friction or viscosity becomes more dominant than the inertial force with conventional machines. Thus, as the mechanism which converts the energy into the movement, a principle of movement such as the electro static attraction force type, piezo-electric type, ultrasonic type, shape-memory alloy type has been newly proposed.
Particularly, because the piezo-electric type device has a large generation force per unit volume, even a small sized device can generates a practical drive force, and it is used for the actuator of the small sized image pick-up apparatus. The main stream of the present piezo-electric type is an inorganic actuator called PZT (Pb (Zr, Ti)O3).
However, because the displacement amount of PZT is very small, for a case where the large displacement amount or large speed is necessary, it is not appropriate. Further, because PZT includes lead, there is a possibility that its use is limited in future.
Further, in the inorganic actuator, its sintering temperature is as high as about 1000° C., for example, when made into MEMS (micro electro mechanical system), there is a problem in the hybrid capability with circuits. Further, a problem that there is no easy fabrication method prevents the inorganic actuator from being MEMS, miniaturized and integrated.
Also with other inorganic small sized actuators, there is a limitation in respective operation envelopment, or there is a problem that the response is insufficient, the mechanism is complicated, or there is a problem that flexibility is not enough, accordingly, the purpose of use is also limited.
To accommodate these problems, the actuator device using a light and flexible organic material is brought into investigation. Generally, because Young ratio of the organic material is low, (flexible), the displacement force is smaller than that of the inorganic material, however, the displacement amount is large. Further, in the fabrication, because the wet-process such as the inkjet method or printing method can be used, the fabrication of low cost or large area is possible, further, the flexible substrate compatibility is also available.
For the fabrication and application of these organic actuator devices, several technologies are reported (for example, refer to Japanese Laid-Open Patent Publication No. 2005-318712, and Non-Patent Document 1).
According to Japanese Laid-Open Patent Publication No. 2005-318712, by using poly methyl methacrylate as the organic material of the actuator device, by press molding, minute protrusions (cylindrical actuator device) are densely arranged on the plane substrate. As an operation the electric energy is converted into the heat, the minute protrusion is inclined by the difference of the expansion coefficient. By giving the phase difference to the electric signal, the phase difference is generated in the occurrence of the inclination of the protrusions, for example, the minute particle on the protrusion can be transferred.
However, the manufacturing becomes simple by using molding, however, the displacement amount is small, further, minute protrusion can not be individually driven. Further, heat is employed for the drive, there is a problem in efficiency and control.
In the non-patent document 1, par-fluoro-polymer electrolyte film is used as the sheet type soft actuator, when it is adhered to the sheet on which TFT elements are formed, the point system display is made. The actuator device formed and arranged on the sheet is the bend type actuator which is bent by the drive voltage, and the actuator is independently driven by the electric signal through respective TFT elements and protruded from the sheet to display the point system.
However, although the manufacturing can be said simpler than the conventional one, when the bend type actuator is used for the purpose of obtaining an enough displacement amount, there is a problem in down-sizing and high integration. An actuator device in which, while large displacement amount is secured, the down-sizing and the high integration hare possible and the manufacturing is simple, is required.
[Non-Patent Document 1]
Kato, Iba, Sekitani, Noguchi, Hizu, “A Flexible, Light weight Braille Sheet Display with Plastic Actuator driven by An Organic Field Effect transistor Active Matrix.” IEEE International Electron Devices Meeting, Washington, D.C., Dec. 5-7, 2005, #5.1, pp. 105-108.
As described above, the actuator of inorganic material is difficult to be made miniaturized or integrated, the manufacturing is also difficult. Further, there is a problem that there is a limitation in the operation environment, or the response is insufficient, the mechanism is complicated, or flexibility is insufficient. PZT which is a mainstream, further, has a problem of environmental load as it contains lead.
The actuator of the organic material has also been developed, however, the problem of miniaturization and integration still exists, and the realized displacement amount can not be sufficient. Further, for the method of manufacturing also, the more simple and effective manufacturing method is required.